The width of the blade of a snowplow can raise problems particularly in the handling, transport and storage of the snowplow. For example, variations in roadway width can be troublesome since a blade that extends beyond the edge of a roadway can damage or even shear off shrubbery and other objects. Moreover, a wide blade may not be within legal width limits for road travel.
Snowplow blade end extensions have been proposed; see, for example, Maura U.S. Pat. No. 4,275,514 which discloses telescoping snowplow blade extensions, and Hine et al. U.S. Pat. No. 4,356,645 disclosing hydraulically controlled pivotably and incrementally positionable snowplow blade extensions.
However, such prior art extendable blade assemblies have a number of disadvantages. Thus, the Maura blade and extension assembly not only appears to be structurally weak, but also appears to be sensitive to certain use conditions (such as the possibility of ice formation between telescopically retracted and adjacent surface portions or in channels).
The Hine et al. blade assembly not only appears to be incapable of blade end extension pivoting beyond a limited acute angle, but also appears to require the use of only small moldboard blade curvature angles (since with relatively large moldboard blade curvature angles significant gaps develop between adjacent end portions as the pivot angle increases between the blade end and the adjacent extension end).
So far as now known, a simple, reliable and economical assembly of snowplow blade and associated blade end extensions has not previously existed whereby each of the blade end extensions is either in an extended and locked blade extended position, or in a fully retracted and locked extension storage position. The present invention provides such an assembly.